Electronic apparatus for measuring the difference of elevation between two points

Abstract

In an electronic apparatus for measuring a difference of elevation between two points, said apparatus comprising: a tube made of a flexible material; a fluid with a low viscosity completely filling said tube; two piezoelectronical pressure transducers each connected to a source of electrical power and mounted at one extremity of the tube in contact with the fluid filling said tube to produce signal a proportional to the pressure of this fluid; electronic means connected to each of said piezoelectrical pressure transducers for processing the signals received from said transducers, said processing means comprising means for generating a signal proportional to the difference between the signals received from the transducers and means for converting said generated signal into a value indicating the difference of elevation between the extremities of the tube, and means for displaying said value indicating the difference of elevation, the improvement wherein it further comprises means for generating a signal proportional to the mean temperature of the fluid filling said tube; and means for correcting said generated signal proportional to the difference between the signals received from the transducers, with said generated signal proportional to the mean temperature in order to compensate any variation of said generated signal due to a variation in the fluid temperature along the tube.

What is claimed is: 
     
       1. An electronic apparatus for measuring a difference of elevation between two points, said apparatus comprising: (a) a tube made of a flexible material;   (b) a fluid with a low viscosity completely filling said tube;   (c) two piezoelectronical pressure transducers each connected to a source of electrical power and mounted at one extremity of the tube in contact with the fluid filling said tube to produce a signal proportional to the pressure of this fluid;   (d) electronic means connected to each of said piezoelectrical pressure transducers for processing the signals received from said transducers, said processing means comprising means for generating a signal proportional to the difference between the signals received from the transducers and means for converting said generated signal into a value indicating the difference of elevation between the extremities of the tube,   (e) means for displaying said value indicating the difference of elevation,   (f) means for generating a signal proportional to the mean temperature of the fluid filling said tube; and   (g) means for correcting said generated signal proportional to the difference between the signals received from the transducers, with said generated signal proportional to the mean temperature in order to compensate any variation of said generated signal due to a variation in the fluid temperature along the tube, wherein: said correcting means comprises means for dividing the signal proportional to the difference of values between the signal received from the transducers by the signal proportional to the mean temperature to give a corrected output signal and   said converting means comprises an analog digital converter receiving the output signal of the dividing means and transmitting a corresponding value indicating the difference of elevation to the displaying means.     
     
     
       2. An electronic apparatus as claimed in claim 1, wherein said processing means are constituted by a micro processor connected to at least one analog-digital converter for converting the signals received from said transducers and the signal proportional to the mean temperature of the fluid into digital values that can be processed by said micro processor, said micro processor sensing said digital values representative of the pressures at both ends of the tuve and of the mean temperature, said microprocessor further computing said digital values altogether to give a computed value representative of the difference of pressures at the extremities of the tube independently of the temperature of the fluid, then comparing the so computed value to a plurality of values corresponding to a plurality of differences of elevation, and finally interpolating from said plurality of values the actual value of the difference of elevation between both extremities of the tube as measured by the apparatus. 
     
     
       3. An electronic apparatus as claimed in claim 2, wherein the plurality of values used for interpoling the actual value of difference of elevation as measured by the apparatus are stocked into a memory which is fixed onto the tube to make it interchangeable. 
     
     
       4. An electronic apparatus for measuring a difference of elevation between two points, said apparatus comprising: (a) a tube made of a flexible material;   (b) a fluid with a low viscosity completely filling said tube;   (c) two piezoelectronical pressure transducers each connected to a source of electrical power and mounted at one extremity of the tube in contact with the fluid filling said tube to produce a signal proportional to the pressure of this fluid;   (d) electronic means connected to each of said piezoelectrical pressure transducers for processing the signals received from said transducers, said processing means comprising means for generating a signal proportional to the difference between the signals received from the transducers and means for converting said generated signal into a value indicating the difference of elevation between the extremities of the tube,   (e) means for displaying said value indicating the difference of elevation,   (f) means for generating a signal proportional to the mean temperature of the fluid filling said tube; and   (g) means for correcting said generated signal proportional to the difference between the signals received from the transducers, with said generated signal proportional to the mean temperature in order to compensate any variation of said generated signal due to a variation in the fluid temperature along the tube, wherein the means for generating a signal proportional to the mean temperature of the fluid comprises an element extending along the tube in the fluid and having a low electrical resistivity, and a voltage reference generator for supplying said element with a stable, D.C. voltage.   
     
     
       5. An electronic apparatus as claimed in claim 4, wherein said processing means are constituted by a micro processor connected to at least one analog digital converter for converting the signals received from said transducers and the signal proportional to the mean temperature of the fluid into digital values that can be processed by said micro processor, said micro processor sensing said digital values representative of the pressures at both ends of the tube and of the mean temperature, said microprocessor further computing said digital values altogether to give a computed value representative of the difference of pressures at the extremities of the tube independently of the temperature of the fluid, then comparing the so computed value to a plurality of values corresponding to a plurality of differences of elevation, and finally interpolating from said plurality of values the actual value of the difference of elevation between both extremities of the tube as measured by the apparatus. 
     
     
       6. An electronic apparatus as claimed in claim 5, wherein the plurality of values used for interpoling the actual value of difference of elevation as measured by the apparatus are stocked into a memory which is fixed onto the tube to make it interchangeable.